[Effect of electroacupuncture intervention on spinal AMPA-receptor expression in rats with neuropathic pain]

To observe the effect of electroacupuncture (EA) intervention on changes of spinal a-amino-3- ydroxy-5-methylisoxazole-4-propionate acid (AMPA) receptor (GluR 1) expression in rats with chronic constrictive injury (CCI) pain, so as to explore its mechanisms underlying improvement of neuropathic pain.

Sixty male SD rats were randomly divided into sham-operation, CCI model and EA groups (n=20). Neuropathic pain model was established by ligature of the right sciatic nerve. EA stimulation (2 Hz, 1-3 mA) was applied to "Weizhong" (BL 40) and "Huantiao" (GB 30) on the injured limb for 30 min, once a day for 7 days beginning from the 11th day on after CCI. The mechanical and thermal pain thresholds were measured before and after the CCI procedure (baseline) and after EA intervention. The AMPA receptor subunit GluR 1 protein and gene expression in L5-L 6 segments of the spinal cord was detected using Western blot (WB), immunohistochemistry and re- verse transcription (RT)-polymerase chain reaction (PCR), separately.

As the results of mechanical and thermal pain thresholds in our past study, EA intervention could markedly raise CCl-reduced decreased pain threshold. Compared with the sham-operation group, the expression levels of spinal GluR 1 protein and mRNA in the model group were significantly increased (P<0.05, P<0.01). Following EA intervention, the expression levels of GluR 1 protein and mRNA were remarkably down-regulated in the EA group in comparison with those of the model group (all P<005).

EA intervention can down-regulate CCI-induced increase of AMPA receptor GIuR 1 expression in the lumbar spinal cord in CCI rats, which may contribute to its effect in alleviating neuropathic pain.